In vivo biomechanical properties of biodegradable polylactic acid-glycolic acid lumbar intertransverse fusion cage

doi:10.3969/j.issn.2095-4344.2014.52.012

Abstract

Abstract:

BACKGROUND: To increase the fusion rate and further reduce complications, Li Kai-nan and co-workers designed an absorbable intertransverse fusion cage made from biodegradable polylactic acid-glycolic acid (PLGA) material (the patent number of State Intellectual Property Office of China: 200810148018.0).

OBJECTIVE: To investigate the biomechanical variation of the biodegradable PLGA lumbar intertransverse fusion cage in vivo.

METHODS: Ninety-six Boer goats were randomly divided into experimental and control groups. The biodegradable PLGA lumbar intertransverse fusion cage was placed in the L_4/5 intertransverse segment in the experimental group; the same size lilac bone was placed in the same position in the control group. The whole lumbar vertebrae were taken to make specimens at 1, 3, 6, 9, 12, 18 months after operation. Three-dimensional spine motion measurement system was used to calculate the range of motion of the L_4/5 segment in the anteflexion, rear extension, left/right lateral bending and rotation states.

RESULTS AND CONCLUSION: Anteflexion, rear extension, lateral bending and rotation motions of both groups reduced successively at 1, 3, 6, 9, 12 and 18 months after operation. The range of anteflexion movements in the experimental group was lower than that of the control group at 3, 9, 12 postoperative months (P < 0.05); the ranges of rear extension, right lateral bending and rotation motions in the experimental group were lower than that of the control group at 1, 3, 9, 12 postoperative months (P < 0.05); the range of left lateral bending movements in the experimental group was lower than that of the control group at 9 and 12 postoperative months (P < 0.05). These results show that the biodegradable PLGA lumbar intertransverse fusion cage in vivo could provide initial mechanical stability in the early stage, avoid stress shielding in the metaphase, and meanwhile it can act as the scaffold for bone formation and make for bone creeping substitution. This fusion cage has better biological properties than autologous iliac bone graft.

中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

全文链接：

Key words: lumbar vertebrae, spinal fusion, biomechanics, biodegradation, environmental

CLC Number:

R318

Yao Bao, Li Kai-nan, Nie Hai. In vivo biomechanical properties of biodegradable polylactic acid-glycolic acid lumbar intertransverse fusion cage [J]. Chinese Journal of Tissue Engineering Research, 2014, 18(52): 8426-8432.

Figures/Tables 1

2.1 实验动物数量分析 96只羊均进入结果分析。 2.2 大体观察结果术后1个月：两组髂骨块表面被松软的纤维结缔组织包裹，周围组织可见充血水肿。实验组融合器也由无色透明变为浑浊的乳白色，表面略微粗糙，轻度软化，融合器周围小孔处及与横突接触处可见极少量的软骨组织和钙化骨生成，融合器未见变形或碎裂，触之较硬。对照组髂骨块与横突间可见软骨组织和少量新生骨生成，髂骨块周围变圆滑，较植入时周围已吸收。两组植入物的活动性均较大，实验组融合器及髂骨块周围均未见变性发黑的组织。术后3个月：两组髂骨块周围可见明显质地较韧的纤维结缔组织包裹，较术后1个月变薄。实验组融合器部分残缺，仍保持原融合器外形，表面粗糙，软化，触之较硬，质脆，融合器与横突、关节突和外侧峡部接触部位可见有少量软骨组织和骨组织形成，髂骨块与横突接触处可见中等量的骨组织生成，纤维结缔组织变薄变韧。对照组有2只未见软骨及骨组织形成，髂骨块周围吸收明显。实验组有1只见融合器在中部横行裂开。两组活动度较差，周围软组织充血水肿较术后1个月减轻，实验组融合器与髂骨块周围未见明显充血水肿变性的组织。术后6个月：两组髂骨块均牢固固定于横突之间，无活动性，周围纤维结缔组织致密，包膜明显变小，部分消失。实验组融合器外观变形，呈乳白色，表面明显粗糙，开始出现大块缺失，质地松软，融合器与横突、关节突和外侧峡部接触部位可见有大量软骨组织和骨组织形成，原融合器缺失部位有纤维组织、软骨和骨组织共存。对照组纤维结缔组织包膜已经完全消失，外侧皮质骨形成，与上下横突及关节突紧密相连。对照组有1只活动度大，横突与髂骨块之间未见连续性骨痂，周围纤维结缔组织增生，局部出现骨质硬化。实验组融合器及余髂骨块周围均未见明显充血水肿的组织。术后9个月：实验组融合器外型消失，残存的融合器碎裂，呈乳白色不透明颗粒状，散在分布于横突间，原融合器部位被新生骨组织替代，组织内未见空洞。对照组外侧皮质骨质地硬。对照组2只活动度大，髂骨块与横突间的骨质增生硬化，未见连续性骨痂形成，周围纤维结缔组织增生。实验组融合器与余髂骨块周围均未见明显充血水肿的组织。两组余标本均无活动性。术后12个月：实验组融合器已经肉眼难辨，偶可见细小乳白色颗粒，原融合器部位均被新生骨组织完全替代，外型与正常骨组织无差别，绝大部分融合器材料已被吸收，组织内部未见空洞形成，未见明显充血水肿的组织，标本均无活动性。对照组2只活动度大，假关节形成，周围纤维结缔组织增生；对照组余标本新生骨已经达到正常骨组织形态，无活动性。术后18个月：实验组融合器已完全消失，肉眼看已看不到融合器的痕迹，原融合器部位均被新生骨组织完全替代，塑形好，外侧可见皮质骨，与正常骨组织无差别，周围均未见明显充血水肿的组织。对照组1只未愈合，假关节形成，周围纤维结缔组织增生；对照组余标本新生骨已经达到正常骨组织形态，骨塑形好，周围可见皮质骨，无活动性。术后18个月标本大体观察实验组和对照组融合率分别为100%，84.4%，采用连续校正的卡方检验，术后6-18个月实验组的融合率高于对照组(P < 0.05)。 2.3 羊腰椎L4、L5三维运动变化见表1。两组前屈、后伸、侧屈、旋转运动范围分别于术后1，3，6，9，12，18个月依次减少，18个月时两组运动范围无差异。实验组术后3，9，12个月前屈运动范围均小于对照组(P < 0.05)，两组术后1，6，18个月前屈运动范围比较差异无显著性意义；实验组术后1，3，9，12个月后伸、旋转、右侧弯运动范围均小于对照组(P < 0.05)，两组术后6，18个月后伸、旋转、右侧弯运动范围比较差异无显著性意义；实验组术后9，12个月左侧弯运动范围均小于对照组(P < 0.05)，两组术后1，3，6，18个月左侧弯运动范围比较差异无显著性意义(图5)。"

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